The present invention relates to audio speakers and systems, particularly to compact speakers and speaker/enclosure systems.
In recent years, the number of applications to which compact speakers are put has grown substantially. This growth is partly due to the arrival of numerous new forms of consumer electronics and personal electronic music playing devices, many of which require or promote the use of accessory speakers for full volume delivery of high quality sound. The increased use of compact speakers has also been fueled by a general trend toward smaller bookshelf or desktop systems, rather than the cabinet work and larger speaker enclosures that had formed the benchmark for audio performance over many decades. Changes in speaker enclosures have proceeded apace, with small speakers mounted in shells or enclosures that may themselves be panel-mounted into a wall or vehicle.
For many of these applications light weight and portability are important. For still others, cost is a major factor. For yet other applications, it may be desirable to optimize the performance of such a speaker in relation to a cabinet or other speaker housing. In such cases, detailed consideration must be given to the structure and acoustics both of the speaker and of the housing. However, the trend to small speakers poses numerous technical problems, especially at the lower frequency end of the spectrum, since a smaller diaphragm is less effective at radiating lower frequencies and, moreover, typically has a higher natural resonance. When bass response is extended or enriched by coupling to a cabinet or enclosure, the enclosure itself must often be deep or bulky. A full panoply of compensatory features, such as the use of higher drive current, longer throw coil constructions, more powerful magnet gap, improved diaphragm materials, folded horn paths and other cabinet configurations may need to be considered to achieve the desired operation in a smaller size system. Moreover, the size of the system depends on the speakers, since the size of a speaker itself may dictate the minimum dimensions physically required for its enclosure.
Another problem arises when it is desired to provide room-filling sound with a composite system, such as a stereo or surround sound system having multiple speakers or speaker diaphragms each optimized for a sub-band of the audio spectrum. In this case, when a plurality of separate instruments such as a chorus, a jazz ensemble, or a quartet are to be heard and individually discerned in the resulting sound, the problem arises that the apparent center or source of the sound may wander or jump from place to place as the pitch changes, even when the pitches had originally been produced by and recorded from the same, stationary, instrument. This problem arises in part because human auditory perception is quite sensitive to phase information, which may change as the sound emanates from different regions—speaker diaphragms or enclosure ports—of the system. This problem has been addressed to some extent by mounting various basic elements, such as a tweeter and a mid-range transducer, concentrically, so that their physical separation is only axial, and is no more than a few inches. However, the portion of sound emanating from the enclosure also contributes to this effect, making the achievement of true pinpoint sound problematic. Moreover, physical dimensions of the various magnet, frame and diaphragm structures making up a speaker or speaker system place limits on the proximity of the different sound sources.
Thus, it would be desirable to provide a speaker of improved compactness.
It would also be desirable to provide a multi-diaphragm or wide range speaker with pinpoint sound definition.
It would also be desirable to provide a housing in which the performance of a compact speaker is further enhanced.
It would also be desirable to devise such a speaker and housing, wherein the housing itself is adapted to be mounted in a cabinet, a wall space or other location as a unit, and to thereby adapt the mounting structure without extensive acoustic engineering or individualized design considerations.